From ef32100342801b0ae3a137449a2aabe8da7c9cda Mon Sep 17 00:00:00 2001
From: David Blaikie <dblaikie@gmail.com>
Date: Mon, 21 Jul 2014 16:26:24 +0000
Subject: [PATCH] Correct the ownership passing semantics of
 object::createBinary and make them explicit in the type system.

createBinary documented that it destroyed the parameter in error cases,
though by observation it does not. By passing the unique_ptr by value
rather than lvalue reference, callers are now explicit about passing
ownership and the function implements the documented contract. Remove
the explicit documentation, since now the behavior cannot be anything
other than what was documented, so it's redundant.

Also drops a unique_ptr::release in llvm-nm that was always run on a
null unique_ptr anyway.

llvm-svn: 213557
---
 include/llvm/Object/Binary.h | 6 ++----
 lib/Object/Archive.cpp       | 2 +-
 lib/Object/Binary.cpp        | 4 ++--
 tools/llvm-nm/llvm-nm.cpp    | 5 ++---
 4 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/include/llvm/Object/Binary.h b/include/llvm/Object/Binary.h
index 9be2fbe0837..91984cb5271 100644
--- a/include/llvm/Object/Binary.h
+++ b/include/llvm/Object/Binary.h
@@ -125,10 +125,8 @@ public:
 
 /// @brief Create a Binary from Source, autodetecting the file type.
 ///
-/// @param Source The data to create the Binary from. Ownership is transferred
-///        to the Binary if successful. If an error is returned,
-///        Source is destroyed by createBinary before returning.
-ErrorOr<Binary *> createBinary(std::unique_ptr<MemoryBuffer> &Source,
+/// @param Source The data to create the Binary from.
+ErrorOr<Binary *> createBinary(std::unique_ptr<MemoryBuffer> Source,
                                LLVMContext *Context = nullptr);
 
 ErrorOr<Binary *> createBinary(StringRef Path);
diff --git a/lib/Object/Archive.cpp b/lib/Object/Archive.cpp
index 3c683408969..e32bdd5c5be 100644
--- a/lib/Object/Archive.cpp
+++ b/lib/Object/Archive.cpp
@@ -181,7 +181,7 @@ Archive::Child::getAsBinary(LLVMContext *Context) const {
   if (std::error_code EC = BuffOrErr.getError())
     return EC;
 
-  return createBinary(*BuffOrErr, Context);
+  return createBinary(std::move(*BuffOrErr), Context);
 }
 
 ErrorOr<Archive *> Archive::create(std::unique_ptr<MemoryBuffer> Source) {
diff --git a/lib/Object/Binary.cpp b/lib/Object/Binary.cpp
index 9f6a68556f9..552d5db89c5 100644
--- a/lib/Object/Binary.cpp
+++ b/lib/Object/Binary.cpp
@@ -38,7 +38,7 @@ StringRef Binary::getFileName() const {
   return Data->getBufferIdentifier();
 }
 
-ErrorOr<Binary *> object::createBinary(std::unique_ptr<MemoryBuffer> &Buffer,
+ErrorOr<Binary *> object::createBinary(std::unique_ptr<MemoryBuffer> Buffer,
                                        LLVMContext *Context) {
   sys::fs::file_magic Type = sys::fs::identify_magic(Buffer->getBuffer());
 
@@ -79,5 +79,5 @@ ErrorOr<Binary *> object::createBinary(StringRef Path) {
       MemoryBuffer::getFileOrSTDIN(Path);
   if (std::error_code EC = FileOrErr.getError())
     return EC;
-  return createBinary(FileOrErr.get());
+  return createBinary(std::move(*FileOrErr));
 }
diff --git a/tools/llvm-nm/llvm-nm.cpp b/tools/llvm-nm/llvm-nm.cpp
index d021a0d341f..15304c40b88 100644
--- a/tools/llvm-nm/llvm-nm.cpp
+++ b/tools/llvm-nm/llvm-nm.cpp
@@ -993,13 +993,12 @@ static void dumpSymbolNamesFromFile(std::string &Filename) {
       MemoryBuffer::getFileOrSTDIN(Filename);
   if (error(BufferOrErr.getError(), Filename))
     return;
-  std::unique_ptr<MemoryBuffer> Buffer = std::move(BufferOrErr.get());
 
   LLVMContext &Context = getGlobalContext();
-  ErrorOr<Binary *> BinaryOrErr = createBinary(Buffer, &Context);
+  ErrorOr<Binary *> BinaryOrErr =
+      createBinary(std::move(*BufferOrErr), &Context);
   if (error(BinaryOrErr.getError(), Filename))
     return;
-  Buffer.release();
   std::unique_ptr<Binary> Bin(BinaryOrErr.get());
 
   if (Archive *A = dyn_cast<Archive>(Bin.get())) {